Create a content factory for a cell.
Create a new cell footer for the parent widget.
Create a new cell header for the parent widget.
Create an input prompt.
Create a new markdown cell widget.
If no cell content factory is passed in with the options, the one on the notebook content factory is used.
Create the output prompt for the widget.
The default implementation of a notebook content factory..
Notes
Override methods on this class to customize the default notebook factory methods that create notebook content.